Port Checker
Check whether TCP ports are open or closed for domains or IP addresses.
Frequently asked questions
What does "port open" mean?
An open port means a service is actively listening and accepting connections. Closed means no service responded. Filtered means a firewall likely blocked the check.
What are common ports?
21=FTP, 22=SSH, 25=SMTP, 53=DNS, 80=HTTP, 110=POP3, 143=IMAP, 443=HTTPS, 465=SMTPS, 587=SMTP Submission, 993=IMAPS, 995=POP3S, 3389=RDP.